1. Field of the Invention
The invention relates to a thermal printing device, and more particularly to a thermal printing device formed by the micromachining technology and applied to the printing market owing to its low power consumption and high resolution. This invention also relates to Taiwan Patent Application No. 092119508, filed on Jul. 17, 2003, and entitled “Ink-Jet Print Head With A Chamber Sidewall Heating Mechanism And A Method For Manufacturing The Same”.
2. Description of the Related Art
A conventional thermal printing head (TPH) prints texts or images on a sheet by way of thermal transfer printing technology using dyes on a black or color ribbon. Unlike the printing technology of the ink-jet print head, the thermal printing device may provide excellent gray-scale effects by controlling the temperature of transfer printing, and may provide the quality approximating the conventional photo printing quality in the aspect of color photo printing.
FIG. 1 is a cross-sectional view showing a conventional thermal printing device. Referring to FIG. 1, the conventional thermal printing device includes a substrate 10, a heat-isolation layer 12, a plurality of heating resistors 14, and a passivation layer 16. The substrate 10 is typically a ceramic substrate having good thermal conductivity. The heat-isolation layer 12, which is composed of, for example, a silicon dioxide material with poor thermal conductivity, is formed on the substrate 10 so that the thermal efficiency of the thermal printing device may be enhanced. The heating resistors 14 are formed on the heat-isolation layer 12, and the passivation layer 16 with the wear-resistant property and the good thermal conductivity is formed on the heating resistors 14 and the heat-isolation layer 12.
However, the conventional thermal printing device still has the drawback of great power consumption owing to the solid heat conductance and thus the drawback of poor heating efficiency. Moreover, the thermal coupling problems between different heating resistors 14 may limit the resolution. Thus, the thermal printing device with high resolution (the current technology may only reach 300 to 400 dpi) cannot be manufactured, and the quality of the printed color photo may be simultaneously limited. On the other hand, the conventional manufacture technology also limits the possibility of integrating the TPH and its corresponding circuits into a single chip.
Accordingly, the invention wishes to provide a micromachined thermal printing device to overcome the conventional problems and drawbacks.